In his new book Searching for What Makes Us Human, in Rainforests, Labs, Sanctuaries, and Zoos, American science journalist Jon Cohen suggests that it might now be time to emphasise the differences between us and our evolutionary cousins.
He writes: ‘There is something fundamentally backward about the "almost human" rubric for chimps. From everything I can tell, no chimpanzee looks at a human and wonders: is this where I came from? Nor do chimps ponder the possibility that we represent where they are heading. Yet humans from every culture look at chimpanzees and see hints of their primitive selves.'
Cohen recounts a number of tales from his travels around the world, when he met both with chimps and their researchers. His journey includes world-renowned genetics labs, rainforests in Uganda, sanctuaries in Iowa, and experimental enclaves in Japan. At times, the book frustratingly reads like a collection of tangentially related articles, where Cohen's argument is often hidden or lost; but nonetheless there are many interesting insights into the world of ape research.
Having investigated the ape-language field for my book Just Another Ape?, I was especially interested in what Cohen had to say about apes' purported ability to acquire human-like language. During one of his journeys, Cohen met two of the stars of the ape-language world: the bonobo Kanzi and his half-sister, Panbanisha. He writes: ‘If they have language, I did not witness it. If a three-year-old human showed as little response to what I said, I would think the child had a hearing problem or was psychologically impaired.'
The 1960s and 70s were the heyday of ape-language research, but the field imploded in the 1980s after Columbia University researcher, Herbert Terrace, published the findings of his attempts to teach the chimp Nim Chimpsky American Sign Language (ASL). Not only did Terrace conclude that Nim was incapable of creating sentences; his team also analysed films of other high-profile ASL-using apes, including Washoe the chimp and Koko the gorilla, and decided that apes had a ‘severely restricted' ability to learn more than ‘isolated symbols.' There was no evidence of them being able to create sentences.
The field became the butt of jokes, Cohen points out, quoting the linguist Noam Chomsky: ‘It's as likely that an ape will prove to have a language ability as there is an island somewhere with a species of flightless birds waiting for humans to teach them to fly.'
At the Wolfgang Köhler Primate Research Centre in Leipzig, Germany, Cohen was given a tour by its director, Josep Call. Call and his team have carried out comparative research on two-year-old human children and adult chimps and orang-utans, and have found that human children significantly outperform apes on social cognition tasks even at this young age. This shows that humans are not just social, Call says, but ‘ultra social'. It is our unique ability to connect with other minds that has allowed us to advance through cumulative cultural transmission.
Back in the US, Cohen spoke to David Premack, the man who came up with the concept of ‘Theory of Mind'. He has carried out extensive comparative research on chimps and humans, concluding that only humans can teach and correct themselves. Premack writes: ‘It is no coincidence that humans both practise and teach, whereas other species do neither. A species that practises but does not teach - that corrects itself but does not correct others - will probably never be found. Nor will a species of the opposite kind, one that teaches but does not practise, [one that] corrects others but not itself.'
Although the field of primate research is littered with anthropomorphism - as Premack told Cohen, too many of his former colleagues were ‘chimp huggers' who ‘confused chimps with humans' - there has been some fascinating research in recent decades, and key theoretical breakthroughs have been made. Cohen is lucky to have had the opportunity to meet so many of those who have been at the forefront of these innovations, and to discuss their findings and insights with them.
